import java.util.ArrayList;
import java.util.List;

public class MyBinaryTree {
    static class TreeNode {
        public char val;
        public TreeNode left;
        public TreeNode right;

        public TreeNode(char val) {
            this.val = val;
        }
    }
    public TreeNode createBinaryTree() {
        TreeNode nodeA = new TreeNode('A');
        TreeNode nodeB = new TreeNode('B');
        TreeNode nodeC = new TreeNode('C');
        TreeNode nodeD = new TreeNode('D');
        TreeNode nodeE = new TreeNode('E');
        TreeNode nodeF = new TreeNode('F');
        TreeNode nodeG = new TreeNode('G');
        TreeNode nodeH = new TreeNode('H');
        nodeA.left = nodeB;
        nodeA.right = nodeC;
        nodeB.left = nodeD;
        nodeB.right = nodeE;
        nodeE.right = nodeH;
        nodeC.left = nodeF;
        nodeC.right = nodeG;
        return nodeA;
    }
    //前序遍历
    public void preOrder(TreeNode root) {
        if(root == null) return;
        System.out.print(root.val+" ");
        preOrder(root.left);
        preOrder(root.right);
    }
    //中序遍历
    public void inOrder(TreeNode root) {
        if(root == null) return;
        preOrder(root.left);
        System.out.print(root.val+" ");
        preOrder(root.right);
    }
    //后序遍历
    public void postOrder(TreeNode root) {
        if(root == null) return;
        preOrder(root.left);
        preOrder(root.right);
        System.out.print(root.val+" ");
    }
    public static int nodeSize;

    /**
     * 获取树中节点的个数：遍历思路
     */
    void size(TreeNode root) {
        if(root == null) return;
        nodeSize ++;
        size(root.left);
        size(root.right);
    }

    /**
     * 获取节点的个数：子问题的思路
     *
     * @param root
     * @return
     */
    int size2(TreeNode root) {
        if(root == null) return 0;
        int m = size2(root.left);
        int n = size2(root.right);
        return m + n + 1;
    }


    /*
     获取叶子节点的个数：遍历思路
     */
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if(root.right == null && root.left == null) {
            leafSize ++;
        }
        getLeafNodeCount1(root.left);
        getLeafNodeCount1(root.right);
    }

    /*
     获取叶子节点的个数：子问题
     */
    int getLeafNodeCount2(TreeNode root) {
        if(root == null) return 0;
        if(root.left == null && root.right == null) {
            return 1;
        }
        return getLeafNodeCount2(root.left) + getLeafNodeCount2(root.right);
    }

    /*
    获取第K层节点的个数
     */
    int getKLevelNodeCount(TreeNode root, int k) {
        if(k == 1) {
            return 1;
        }
        return getKLevelNodeCount(root.left,k-1) + getKLevelNodeCount(root.right,k-1);
    }

    /*
     获取二叉树的高度
     时间复杂度：O(N)
     */
    int getHeight(TreeNode root) {
        if(root == null) {
            return 0;
        }
        int left = getHeight(root.left);
        int right = getHeight(root.right);
        return left > right ? left + 1 : right + 1;
    }


    // 检测值为value的元素是否存在
    boolean find(TreeNode root, char val) {
        if(root == null) {
            return false;
        }
        if(root.val == val) {
            return true;
        }
        boolean left = find(root.left,val);
        if(left == true) {
            return true;
        }
        boolean right = find(root.right,val);
        if(right == true) {
            return true;
        }
        return false;
    }

}
